JP2004255738A - Tire retreading method and retreaded tire obtained by the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively inhibit for a long time separation between a tread rubber strip and a casing in a regenerated tire obtained by a precuring method. <P>SOLUTION: In the tread rubber strip 12, a rubber thickness Ts at the outer end edge eo thereof is made 40-95% of a rubber thickness Tc at the tread equator. A sipe 15 extending in the length direction is formed at a position located in a shoulder land part along the outer end edge eo and spaced at a distance of 8-16 mm from this edge, while the depth of the sipe is made 20-90% of a rubber thickness Tu at the position of the above formation. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a precuring type tire rehabilitation method for suppressing separation of a precured tread rubber band from a base tire, and a rehabilitating tire using the same.
[0002]
2. Description of the Related Art
As one of the tire rehabilitation methods, as shown in FIG. 6, a tread rubber is removed from a used tire to obtain a base tire a, and a tread forming surface a1 of the base tire a (a surface from which the tread rubber is removed). A precured tread rubber band c preliminarily vulcanized and formed is bonded to the precured tread rubber band c via an unvulcanized rubber sheet b for bonding. A system of the type is known (for example, see Patent Document 1).
[0003]
In such a system, as described in Patent Document 1, as the tread rubber band c, one having a constant rubber thickness t over the entire range from one end edge to the other end edge of its surface is widely used. .
[0004]
However, in the retreaded tire using such a tread rubber band c, in the shoulder region of the tread, the contact pressure becomes relatively high, and an external force (for example, a lateral force) input from a road surface acts greatly. Therefore, when used on a road with a lot of winding such as an urban area or a mountain area, or when used under severe conditions in which excessive twisting is applied to the tire, the outer surface of the interface between the tread rubber band c and the base tire a is not provided. There is a problem that separation easily occurs starting from the end.
[0005]
In order to solve this problem, for example, Patent Document 2 proposes a technique in which a rubber thickness t in a shoulder region of a tread rubber band c is gradually reduced toward an outer end. However, even in such a case, when the crown region at the center of the tread is worn due to running and the difference in the rubber thickness t between the crown region and the shoulder region becomes small, the contact pressure in the shoulder region increases, and the effect of suppressing the separation is reduced. There is a problem that it is not sufficiently exhibited.
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 9-70903 [Patent Document 2]
JP 2001-294019 A
Therefore, the present invention, in the tread rubber band, at least reduce the rubber thickness of the shoulder region to the outer edge, and specify the ratio of the rubber thickness at the outer edge and the rubber thickness at the tread equator, A tire rehabilitation method capable of exhibiting the effect of suppressing separation of a tread rubber band for a long period of time on the basis of forming a siping extending in a longitudinal direction at a predetermined position of a shoulder land portion along the outer edge, and rehabilitation thereby. It aims to provide tires.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 of the present application is a tire rehabilitation method for attaching a precured tread rubber band whose front surface forms a tread surface by attaching a back surface to a tread forming surface of a base tire. ,
By forming the surface of the tread rubber band as a single arc in a cross section including the tire axis, the rubber thickness T between the back surface and the front surface in a direction perpendicular to the surface is set to the tread equator side. From the surface toward the outer edge of the surface;
In addition, the rubber thickness Ts at the outer edge is set to 40 to 95% of the rubber thickness Tc at the tread equator,
On the surface, a vertical main groove of a tire, a block arranged along the outer edge by providing a concave portion for forming a horizontal main groove, or forming a shoulder land portion composed of a rib,
Moreover, a siping extending in the length direction is formed in the shoulder land portion and at a position separated from the outer edge by a distance of 8 to 16 mm, and the depth thereof is set to 20 to the rubber thickness Tu at the position. It is characterized by being 90%.
[0009]
Further, in the invention of claim 2, the surface of the tread rubber band has a surface in a crown region between positions which are separated from the tread equator on both sides by a distance of 15 to 40% of a tread rubber width between outer edges thereof. In the shoulder region where the rubber thickness T in the perpendicular direction is constant and reaches the outer edge on the outer side, the surface is formed into a single arc so that the rubber thickness from the inner edge to the outer edge of the shoulder region is increased. Decrease T
In addition, the rubber thickness Ts at the outer edge is set to 40 to 95% of the rubber thickness Tc at the tread equator,
On the surface, a vertical main groove of a tire, a block arranged along the outer edge by providing a concave portion for forming a horizontal main groove, or forming a shoulder land portion composed of a rib,
Moreover, a siping extending in the length direction is formed in the shoulder land portion and at a position separated from the outer edge by a distance of 8 to 16 mm, and the depth thereof is set to 20 to the rubber thickness Tu at the position. It is characterized by being 90%.
[0010]
According to the third aspect of the present invention, the tread rubber band has both side walls inclined in a direction to reduce the tread rubber width toward the front surface, and a compression extending in a length direction at a portion near the back surface of the side wall. It is characterized in that a concave groove for strain relaxation is formed.
[0011]
In the invention according to claim 4, the base tire is characterized in that the tread affixing surface is a single arc having a curvature radius R0 of 500 to 600 mm in a cross section including the tire axis.
[0012]
A fifth aspect of the present invention is an invention of a retreaded tire, which is retreaded using the precured tread rubber band according to any one of the first to fourth aspects.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to illustrated examples.
FIG. 1 is a partial cross-sectional view showing a main part of a base tire used in the tire rehabilitation method of the present invention, and FIG. 2 is a cross-sectional view showing a precured tread rubber band to be attached thereto.
[0014]
As shown conceptually in FIG. 5, the tire rehabilitation method of the present invention uses a precured tread via a non-vulcanized rubber sheet b (about 1 mm thick) for bonding on the tread forming surface 11s of the base tire 11. This is a so-called pre-cure rehabilitation method in which a rubber band 12 is adhered, and the tire to which the tread rubber band 12 is adhered is heated in a vulcanized can g or the like in an inflated state in which the tire is assembled into a rim and filled with internal pressure. Thereby, the retreaded tire 1 in which the tread rubber band 12 and the base tire 11 are vulcanized and bonded is formed.
[0015]
Here, as shown in FIG. 1, the base tire 11 is formed by removing a tread rubber G from a used tire by buffing or the like. It is preferable that the tread forming surface 11s, which is a surface from which the tread rubber G is removed, is formed in an arc shape substantially along the contour shape of the widest belt ply in the belt layer 7. In this example, the case where the belt layer 7 is formed from three or more, for example, four belt plies using a metal cord as the belt cord is exemplified, and the second belt layer from the innermost in the radial direction is second. The ply width of the belt ply 7B is maximized. Therefore, in the present example, the tread forming surface 11s is formed in an arc shape along the outer surface of the second belt ply 7B. In the case of a heavy load tire or a light truck tire, the tread forming surface 11s is formed substantially along the outer surface of the second belt ply 7B by making the radius of curvature R0 a single arc of 500 to 600 mm. can do.
[0016]
Next, the tread rubber band 12 is a vulcanized band-shaped tread rubber preliminarily vulcanized and formed in a press die, and as shown in FIG. Reference numeral 12 has a substantially trapezoidal cross section having a back surface Sr attached to the tread forming surface 11s and a front surface Sf forming a tread surface.
[0017]
More specifically, in the tread rubber band 12 according to the first invention, in this example, the back surface Sr is formed by a plane parallel to the tire axis, and the front surface Sf is formed by a single center having a center on the tread equatorial plane Co. Of the circular arc K1. Thereby, the rubber thickness T between the back surface Sr and the front surface Sf in a direction perpendicular to the front surface Sf is reduced from the tread equator C side toward the outer edge eo of the front surface Sf. At this time, the rubber thickness Ts at the outer edge eo is set in a range of 40 to 95% of the rubber thickness Tc at the tread equator C.
[0018]
The back surface Sr may be a single arc having a center on the tread equatorial plane Co. In such a case, for example, the front surface Sf is obtained by adding the rubber thickness Tc to the radius of curvature of the back surface Sr. The rubber thickness T can be reduced from the side of the tread equator C toward the outer edge eo by, for example, forming a single arc having a radius of curvature smaller than the radius of curvature.
[0019]
When the tread rubber band 12 is vulcanized and formed, a tread pattern including a concave portion 13 for forming a vertical main groove and a horizontal main groove of the tire is formed on the surface Sf. Here, the concave portion 13 includes an outermost vertical concave portion 13A extending continuously along the outer edge eo, whereby a shoulder land portion 14 is provided between the vertical concave portion 13A and the outer edge eo. Is formed. The shoulder land portion 14 may be a rib body extending continuously along the outer edge eo, or may be a block row in which blocks are arranged along the outer edge eo.
[0020]
In the shoulder land portion 14, a siping 15 extending in the length direction (corresponding to the tire circumferential direction) is formed at a position separated by a distance L1 of 8 to 16 mm from the outer edge eo. Moreover, the depth D of the siping 15 is set to 20 to 90% of the rubber thickness Tu at the position where the siping 15 is formed.
[0021]
As shown in FIG. 3, the retreaded tire 1 using the tread rubber band 12 configured as described above has a rubber thickness T that decreases from the tread equator side to the outer edge eo, so that the radius of curvature R of the tread surface is reduced. However, the size is smaller than that of a conventional retreaded tire. Therefore, in the shoulder region, the external force (for example, lateral force) input from the road surface can be reduced, and the stress (shear stress and tensile stress) acting on the outer end of the interface between the tread rubber band 12 and the base tire 11 is reduced, Separation starting from the outer end can be suppressed. At this time, the applied load gradually increases toward the tread equator, so that the durability of the tire can be maintained.
[0022]
In addition, the decrease of the rubber thickness T toward the outer edge eo reduces the internal heat generation in the shoulder region during running, so that the thermal deterioration of the rubber can be suppressed, and the effect of suppressing the separation is further enhanced. It becomes possible.
[0023]
Further, in order to sufficiently exert such effects, the rubber thickness Ts needs to be 40 to 95% of the rubber thickness Tc, as described above. The effect of suppressing the above is not exhibited. Conversely, if it is less than 40%, the load applied to the tread equator side becomes excessive, for example, the tread equatorial side protrudes too outward in the tire radial direction, resulting in a decrease in tire durability. From such a viewpoint, it is preferable that the rubber thickness Ts be in the range of 60 to 80% of the rubber thickness Tc.
[0024]
Further, the siping 15 provided on the shoulder land portion 14 has an effect of alleviating an external force (for example, a lateral force) received from a road surface from acting on the outer edge of the interface. Accordingly, even when the wear on the tread equatorial side progresses and the difference between the rubber thicknesses Ts and Tc decreases, and the operation effect decreases, the siping 15 acts on the outer edge of the interface. Stress (shear stress and tensile stress) can be reduced. Therefore, it is possible to exhibit the effect of suppressing the separation over a long period of time.
[0025]
If the depth D of the sipe 15 is less than 20% of the rubber thickness Tu, the sipe 15 itself tends to disappear due to abrasion, so that the effect of reducing the external force cannot be achieved in the middle to late stages of abrasion. On the other hand, if it exceeds 90%, the sipe 15 is too deep and the rigidity is too small, causing a decrease in steering stability and a tendency for rubber to be chipped outside the sipe 15. From such a viewpoint, the depth D is preferably set to 40 to 60% of the rubber thickness Tu.
[0026]
If the distance L1 between the sipe 15 and the outer edge eo is less than 8 mm, the rigidity is too small to cause a decrease in steering stability, and the rubber tends to be chipped outside the sipe 15. On the other hand, if it exceeds 16 mm, the rigidity becomes excessively large and the effect of alleviating the external force is inferior, and the effect of suppressing the separation cannot be exhibited. From such a viewpoint, it is more preferable that the distance L1 be in the range of 10 to 12 mm.
[0027]
In the case where the shoulder land portion 14 has a large width and a greater external force reducing effect is required as in this example, another siping 16 (shown in FIG. 2) is further provided inside the siping 15. One or more can be provided. At this time, the siping 16 is preferably formed at a pitch L2 of 8 to 16 mm from the siping 15, and in particular, it is more preferable to make the pitch L2 equal to the distance L1 from the viewpoint of uneven wear and lack of rubber. preferable.
[0028]
In the tread rubber band 12, both side walls So are inclined in a direction to reduce the tread rubber width toward the front surface Sf. In this example, a portion of the side wall So close to the back surface Sr is provided with a compression strain reducing portion. Are formed. The “portion close to the back surface Sr” means a sectioned area on the back surface Sr side when the side wall So is divided into two equal parts in the thickness direction, and preferably, on the back side Sr side when divided into three equal parts. It means a division area. The concave groove 20 has a U-shaped cross section, a U-shaped cross section, or a semicircular cross section, and extends continuously or discontinuously in the length direction. The groove 20 is preferably formed with a groove width of 4 to 7 mm and a groove depth of 2 to 3.5 mm.
[0029]
The concave groove 20 can relieve and absorb the repetitive compressive strain caused by the contact / non-contact during rotation of the tire, reduce the stress at the outer end of the interface, reduce the distribution of the rubber thickness T, and reduce the Together with the formation, the effect of suppressing separation can be further improved.
[0030]
Next, FIG. 4 illustrates the tread rubber band 32 according to the second invention.
In the tread rubber band 32, in the present embodiment, the back surface Sr is formed as a plane parallel to the tire axis, and the distance L3 of 15 to 40% of the tread rubber width WT between the outer edges eo, eo is set at the tread equator. In the crown region Yc between the positions separated from both sides from C, the front surface Sfc is a plane parallel to the back surface Sr, so that the rubber thickness T is constant. Further, in the shoulder region Ys outside the crown region Yc, the surface Sfs is formed into a single arc K2, so that the rubber thickness T is reduced from the inner edge ei to the outer edge eo of the shoulder region Ys. I have. At this time, the rubber thickness Ts at the outer edge eo is set in the range of 40 to 95% of the rubber thickness Tc at the tread equator C, similarly to the tread rubber band 12 according to the first invention. I have.
[0031]
The back surface Sr may be a single arc having a center on the tread equatorial plane Co. In such a case, the front surface Sfc is obtained by adding the rubber thickness Tc to the radius of curvature of the back surface Sr. By forming a single arc having a radius of curvature equal to the value, the rubber thickness T in the crown region Yc can be made constant. At this time, by making the surface Sfs of the shoulder region Ys an arc having a smaller radius of curvature than the radius of curvature of the crown region Yc, the rubber thickness T is reduced from the inner edge ei to the outer edge eo of the shoulder region Ys. sell.
[0032]
In the tread rubber band 32, the siping 15 is formed in the shoulder land portion 14 and at a position separated from the outer edge eo by a distance L1 of 8 to 16 mm, and the depth D of the siping 15 is set to the rubber thickness Tu. Other than the contour of the surface Sf, such as 20 to 90%, the tread rubber band 12 according to the first invention is formed in the same configuration.
[0033]
Like the tread rubber band 12, such a tread rubber band 32 can exhibit an excellent separation suppression effect over a long period of time. Further, in the tread rubber band 12, since the rubber thickness T changes smoothly from the tread equator to the outer edge, a load tends to be applied on the entire tread surface, so that the tire has high durability. On the other hand, when the rubber thickness T has a constant crown region Yc as in the tread rubber band 32, the contact load applied to the crown region Yc tends to increase as compared with the shoulder region Ys, and the tire Durability may be impaired. However, in the second invention, since the distance L3 of the crown region Yc is set to 15% or more of the tread rubber width WT to balance the ground contact load, it is possible to suppress a decrease in durability. If the distance L3 exceeds 40% of the tread rubber width WT, the shoulder region Ys becomes too small, and the reduction in external force (for example, lateral force) received from the road surface is reduced, and the effect of suppressing separation is insufficient. It will be.
[0034]
As described above, particularly preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to the illustrated embodiments, and can be implemented in various forms.
[0035]
【The invention's effect】
As described above, the present invention reduces the rubber thickness of at least the shoulder region to the outer edge of the precured tread rubber band, and reduces the ratio of the rubber thickness at the outer edge to the rubber thickness at the tread equator. And a siping extending in the longitudinal direction is formed at a predetermined position of the shoulder land portion along the outer edge. Therefore,
It is possible to effectively suppress the paration between the tread rubber band and the base tire over a long period from the initial use to the end.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main part of a base tire used in a tire rehabilitation method of the present invention.
FIG. 2 is a cross-sectional view showing a pre-cured tread rubber band to be attached thereto.
FIG. 3 is a sectional view showing a main part of a retreaded tire using the same.
FIG. 4 is a sectional view showing another tread rubber band of the present invention.
FIG. 5 is a diagram conceptually showing a tire rehabilitation method.
FIG. 6 is a diagram illustrating a conventional technique.
[Explanation of symbols]
11 tire 11s tread forming surface 12 tread rubber band 13 recess 13A recess 14 shoulder land portion 15 siping 20 concave groove 32 tread rubber band Sf front surface Sr back surface So side wall Yc crown region Ys shoulder region

Claims (5)

A tread forming surface of the base tire, a tire rehabilitation method of pasting a pre-cured tread rubber band whose surface forms a tread surface by pasting the back surface,
By forming the surface of the tread rubber band as a single arc in a cross section including the tire axis, the rubber thickness T between the back surface and the front surface in a direction perpendicular to the surface is set to the tread equator side. From the surface toward the outer edge of the surface;
In addition, the rubber thickness Ts at the outer edge is set to 40 to 95% of the rubber thickness Tc at the tread equator,
On the surface, a vertical main groove of a tire, a block arranged along the outer edge by providing a concave portion for forming a horizontal main groove, or forming a shoulder land portion composed of a rib,
In addition, a siping extending in the longitudinal direction is formed in the shoulder land portion and at a position separated by a distance of 8 to 16 mm from the outer edge, and the depth of the siping is set to 20 to 20 of the rubber thickness Tu at the position. A tire rehabilitation method characterized by being 90%. A tread forming surface of the base tire, a tire rehabilitation method of pasting a pre-cured tread rubber band whose surface forms a tread surface by pasting the back surface,
The surface of the tread rubber band has a rubber thickness T in a direction perpendicular to the surface in a crown region between positions that are 15 to 40% of the tread rubber width between the outer edges and separated from the tread equator on both sides. Is constant, and in the shoulder region reaching the outer edge on the outer side, the surface is formed as a single arc to reduce the rubber thickness T from the inner edge to the outer edge of the shoulder region,
In addition, the rubber thickness Ts at the outer edge is set to 40 to 95% of the rubber thickness Tc at the tread equator,
On the surface, a vertical main groove of a tire, a block arranged along the outer edge by providing a concave portion for forming a horizontal main groove, or forming a shoulder land portion composed of a rib,
Moreover, a siping extending in the length direction is formed in the shoulder land portion and at a position separated from the outer edge by a distance of 8 to 16 mm, and the depth thereof is set to 20 to the rubber thickness Tu at the position. A tire rehabilitation method characterized by being 90%. The tread rubber band has both side walls inclined in a direction to reduce the tread rubber width toward the surface, and a groove for compressive strain relief extending in the length direction is formed in a portion of the side wall close to the back surface. The tire rehabilitation method according to claim 1 or 2, wherein: The tire rehabilitation method according to any one of claims 1 to 3, wherein the base tire has a tread affixing surface formed into a single circular arc having a curvature radius R0 of 500 to 600 mm in a cross section including the tire axis. A retreaded tire retreaded using the precured tread rubber band according to any one of claims 1 to 4.

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